[Federal Register Volume 82, Number 120 (Friday, June 23, 2017)]
[Rules and Regulations]
[Pages 28582-28588]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-13162]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2015-0028; FXES11130900000-178-FF09E42000]
RIN 1018-AX99


Endangered and Threatened Wildlife and Plants; Removal of the 
Hualapai Mexican Vole From the Federal List of Endangered and 
Threatened Wildlife

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: Under the authority of the Endangered Species Act of 1973, as 
amended (Act), we, the U.S. Fish and Wildlife Service (Service), are 
removing the Hualapai Mexican vole (Microtus mexicanus hualpaiensis) 
from the Federal List of Endangered and Threatened Wildlife due to 
recent data indicating that the original classification is now 
erroneous. This action is based on a thorough review of the best 
available scientific and commercial information, which indicates that 
the currently listed subspecies is not a valid taxonomic entity. 
Therefore, we are removing the entry for the Hualapai Mexican vole from 
the Federal List of Endangered and Threatened Wildlife because 
subsequent investigations have shown that the best scientific or 
commercial data available when the subspecies was listed were in error.

DATES: This rule is effective July 24, 2017.

ADDRESSES: This final rule is available on the Internet at http://www.regulations.gov under Docket No. FWS-R2-ES-2015-0028 and at the 
Service's Web sites at http://www.fws.gov/southwest/es/arizona and 
http://www.fws.gov/endangered. Comments and materials received, as well 
as supporting documentation used in the preparation of this rule, are 
available for public inspection, by appointment, during normal business 
hours at: U.S. Fish and Wildlife Service, Arizona Ecological Services 
Field Office, 9828 North 31st Avenue, Phoenix, AZ 85051; telephone 602-
242-0210. Persons who use a telecommunications device for the deaf 
(TDD) may call the Federal Relay Service at 800-877-8339.

FOR FURTHER INFORMATION CONTACT: Steven Spangle, Field Supervisor, U.S. 
Fish and Wildlife Service, Arizona Ecological Services Field Office 
(see ADDRESSES), telephone 602-242-0210. Individuals who are hearing 
impaired or speech-impaired may call the Federal Relay Service at 800-
877-8339 for TTY assistance.

SUPPLEMENTARY INFORMATION:

Background

    Under the Endangered Species Act of 1973, as amended (Act; 16 
U.S.C. 1531 et seq.), we administer the Federal Lists of Endangered and 
Threatened Wildlife and Plants, which are set forth in title 50 of the 
Code of Federal Regulations at part 17 (50 CFR 17.11 and 17.12). The 
factors for listing, delisting, or reclassifying species are described 
at 50 CFR 424.11. According to section 3(16) of the Act, we may list 
any of three categories of vertebrate animals: A species, subspecies, 
or a distinct population segment of a vertebrate species of wildlife. 
We refer to each of these categories as a ``listable entity.'' If we 
determine that there is a species, or ``listable entity,'' for the 
purposes of the Act, our status review next evaluates whether the 
species meets the definitions of an ``endangered species'' or a 
``threatened species'' because of any of the five listing factors 
established under section 4(a)(1) of the Act. Delisting may be 
warranted as a result of: (1) Extinction; (2) recovery; or (3) a 
determination that the original scientific data used at the time the 
species was listed, or interpretation of that data, were in error. We 
examine whether the Hualapai Mexican vole is a valid subspecies, and 
thus a ``species'' (or listable entity) as defined in section 3 of the 
Act.

Previous Federal Actions

    We listed the Hualapai Mexican vole as an endangered subspecies on 
October 1, 1987, without critical habitat (52 FR 36776). At the time of 
listing, the primary threats to the Hualapai Mexican vole were degraded 
habitat due to drought, elimination of ground cover from grazing by 
livestock and elk (Cervus elaphus), and human recreation. A recovery 
plan for the Hualapai Mexican vole was completed in August 1991 
(Service 1991, pp. 1-28). At that time, grazing, mining, road 
construction, recreational uses, erosion, and nonnative wildlife were 
attributed as the reasons for the decline in Hualapai Mexican vole 
populations (Service 1991, pp. iv-6). The recovery plan outlined 
recovery objectives and dictated management and research priorities, 
but did not contain recovery criteria for changing the subspecies' 
status from endangered to threatened (i.e., downlisting) or for 
removing the subspecies from the List of Endangered and Threatened 
Wildlife (i.e., delisting) because of lack of biological information in 
order to develop objective, measurable criteria (Service 1991, p. iv).

Petition History

    On August 23, 2004, we received a petition dated August 18, 2004, 
from the Arizona Game and Fish Department (AGFD) requesting that the 
Hualapai Mexican vole be removed from the Federal List of Endangered 
and Threatened Wildlife (List) under the Act. The petition clearly 
identified itself as such and included the requisite identification 
information for the petitioners, as required at 50 CFR 424.14(a). 
Included in the petition was information in support of delisting the 
Hualapai Mexican vole based on an error in original classification due 
to evidence that the Hualapai Mexican vole is not a valid subspecies.
    The petition asserts that the original scientific data used at the 
time the subspecies was classified were in error and that the best 
available scientific data do not support the taxonomic recognition of 
the Hualapai Mexican vole as a distinguishable subspecies (AGFD 2004, 
p. 4). The petition's assertions are primarily based on the results of 
an unpublished genetic analysis (Busch et al. 2001) and on taxonomic 
and genetic reviews of Busch et al.'s 2001 report. The petition did not 
claim that the Hualapai Mexican vole is extinct or has been recovered 
(no longer an endangered or threatened species), nor do we have 
information in our files indicating such. However, the petition did 
indicate that ``fieldwork and genetic analyses have documented at least 
seven, but likely 14, populations (including one in Utah) of M. m. 
hualpaiensis.'' Only one population was known at the time of listing.
    On May 15, 2008, we announced a 90-day finding in the Federal 
Register (73 FR 28094) that the petition presented substantial 
information to indicate that the petitioned action may be warranted. On 
June 4, 2015, we published a warranted 12-month finding on the petition 
and a proposed rule to remove the Hualapai Mexican vole from the List 
because the original scientific classification is no longer the 
appropriate determination for the subspecies (80 FR 31875), meaning 
that

[[Page 28583]]

current data indicate that the original classification is now 
erroneous. On December 22, 2016, we reopened the comment period on the 
proposed rule to remove the Hualapai Mexican vole from the List (81 FR 
93879). We published a summary of the proposed rule in the Kingman 
Daily Miner newspaper on January 29, 2017.

Species Description

Taxonomy

    Goldman (1938, pp. 493-494) described and named the Hualapai 
Mexican vole as Microtus mexicanus hualapaiensis in 1938 based on four 
specimens. Cockrum (1960, p. 210), Hall (1981, p. 481), and Hoffmeister 
(1986, pp. 444-445) all recognized Goldman's description of the 
subspecies, and Hoffmeister (1986, pp. 444-445) further recognized the 
Microtus mexicanus hualapaiensis subspecies based on an examination of 
morphological characteristics from seven additional specimens collected 
in two areas (i.e., Hualapai Mountains and the lower end of Prospect 
Valley).
    Based on morphological measurements, the Hualapai Mexican vole was 
previously considered one of three subspecies of Mexican voles 
(Microtus mexicanus) in Arizona (Kime et al. 1995, p. 1). The three 
subspecies of Mexican voles were the Hualapai Mexican vole (M. m. 
hualapaiensis), Navajo Mexican vole (M. m. navaho), and Mogollon 
Mexican vole (M. m. mogollonensis). The Hualapai Mexican vole differed 
from the Navajo Mexican vole subspecies by a slightly longer body, 
longer tail, and longer and broader skull (Hoffmeister 1986, p. 443). 
Additionally, the Navajo Mexican vole's range was farther to the 
northeast. The Hualapai Mexican vole was also differentiated from the 
Mogollon Mexican vole subspecies, located farther to the east, by a 
longer body, shorter tail, and longer and narrower skull (Hoffmeister 
1986, p. 443).
    The final rule listing the Hualapai Mexican vole as an endangered 
species (52 FR 36776; October 1, 1987) stated that this subspecies 
occupied the Hualapai Mountains, but also acknowledged that Spicer et 
al. (1985, p. 10) had found similar voles from the Music Mountains, 
which are located farther to the north in Arizona. The final listing 
rule (52 FR 36776; October 1, 1987) also stated that Hoffmeister (1986, 
p. 445) had tentatively assigned specimens from Prospect Valley to the 
Hualapai Mexican vole subspecies, pending a larger sample size. In 
addition, the final listing rule (52 FR 36776; October 1, 1987) stated 
that if future taxonomic evaluation of voles from the Music Mountains 
and Prospect Valley should confirm that they are indeed the Hualapai 
Mexican vole subspecies, then they would be considered part of the 
federally listed entity. However, we never recognized Hualapai Mexican 
voles outside of the Hualapai Mountains. Mountains due to insufficient 
data to support recognition of additional populations.
    In May 1998, we reviewed Frey and Yates' 1995 unpublished report, 
``Hualapai Vole (Microtus mexicanus hualapaiensis) Genetic Study,'' to 
determine if Hualapai Mexican voles occur in additional areas outside 
of the Hualapai Mountains. We found that the report did not provide 
sufficient data for us to conclude that populations outside the 
Hualapai Mountains were Hualapai Mexican voles. On May 29, 1998, the 
Southwest Regional Director's Office issued a memo to the Arizona 
Ecological Services Field Office stating that the Service would only 
consult on voles in the Hualapai Mountains until further investigations 
result in data definitive enough to establish that the Hualapai Mexican 
vole has a wider distribution than recognized at the time of listing. 
Thus, we referenced the memo in all requests for consultations on 
Federal projects outside the Hualapai Mountains. For these reasons, we 
have only considered the Hualapai Mexican vole's range to be the 
Hualapai Mountains.
    Since the Hualapai Mexican vole was listed in 1987 (52 FR 36776; 
October 1, 1987), several focused surveys of the subspecies' 
distribution, habitat requirements, and genetic relationships to other 
Mexican vole subspecies were undertaken. We briefly describe these 
studies below. Researchers did not collect or analyze samples from the 
same locations, so locations and analyses across studies do not 
necessarily correlate fully. These studies represent the best 
scientific information available for the Service to analyze the 
Hualapai Mexican vole's distribution and taxonomic classification.
    At the time of listing, we recognized the Hualapai Mexican vole as 
one of three subspecies of Mexican voles in Arizona based on Goldman 
(1938, pp. 493-494), Hall (1981, p. 481), and Hoffmeister (1986, p. 
443). Since that time, Frey and LaRue (1993, pp. 176-177) referred to 
voles in Arizona, New Mexico, and Texas as Microtus mogollonensis 
rather than Microtus mexicanus. In an unpublished genetic analysis 
study on the Hualapai Mexican vole, Frey and Yates (1995) referred to 
the Hualapai Mexican vole subspecies as Microtus mogollonensis 
hualpaiensis. Also, in a study of montane voles, Frey (2009, p. 219) 
supported the earlier study conducted by Frey and LaRue (1993, pp. 176-
177), which separated the vole species Microtus mogollonensis and 
Microtus mexicanus. The Integrated Taxonomic Information System \1\ 
(ITIS) indicates that Microtus mexicanus hualpaiensis (Goldman, 1938) 
is an invalid taxon and indicates that the valid taxon is Microtus 
mexicanus for the Hualapai Mexican vole (http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=202377). For 
consistency with all previous Federal actions, including the scientific 
name that appears on the Federal List of Endangered and Threatened 
Wildlife, we refer to the Hualapai Mexican vole subspecies as Microtus 
mexicanus hualpaiensis in this rule because that is the entity we 
listed in 1987. However, many of the reviewers and documents that are 
referenced refer to voles in Arizona as Microtus mogollonensis. The 
ITIS indicates that Microtus mogollonensis (Frey and LaRue 1993, pp. 
176-177) is an invalid taxon; and indicates that the valid taxon is 
Microtus mexicanus for the Hualapai Mexican vole (http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=202377).
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    \1\ ITIS is the result of a partnership of Federal agencies 
formed to satisfy their mutual needs for scientifically credible 
taxonomic information. An overriding goal of the ITIS project is to 
provide accurate, scientifically credible, and current taxonomic 
data that meet the needs of the ITIS partners and the user public.
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    In a 1989 unpublished Master's thesis, Frey conducted an extensive 
study of geographic variation of specimens from throughout the range of 
the Microtus mexicanus group, which included populations in the United 
States and Mexico. Frey (1989) analyzed 44 external and 19 cranial 
characters from 1,775 vole specimens. Based on morphological analysis, 
Frey (1989, p. 50) recommended that specimens from the Bradshaw 
Mountains (Coconino County, AZ), which was formerly considered the 
Mogollon Mexican vole subspecies, be reassigned to the Hualapai Mexican 
vole subspecies. Frey (1989, p. 50) concluded that two specimens that 
had been discovered from the Music Mountains (Mohave County, AZ) were 
morphologically distinct from other recognized subspecies, and these 
two specimens represented a previously unrecognized taxonomy. Frey's 
(1989) study did not include specimens from Prospect Valley.
    Frey and Yates (1993, pp. 1-23) conducted a genetic analyses of

[[Page 28584]]

Hualapai Mexican vole tissue samples taken from 83 specimens across 13 
populations using electrophoresis and mitochondrial DNA. The 13 
populations represented all 3 subspecies in Arizona and 1 population 
from Mexico (Frey and Yates 1993, p. 20). Their results showed that 
three populations (i.e., Hualapai Mountains, Hualapai Indian 
Reservation, and Music Mountains) form a closely related group distinct 
from other populations in Arizona (Frey and Yates 1993, p. 10). 
According to their analysis, populations in the Hualapai Mountains, 
Hualapai Indian Reservation, and Music Mountains could be regarded as 
the Hualapai Mexican vole subspecies. Further, Frey and Yates (1993, p. 
10) found that the Navajo Mexican vole subspecies populations for San 
Francisco Peaks and the Grand Canyon occurred in a clade (i.e., related 
by a common ancestor) with the Mogollon Mexican vole subspecies 
populations along the Mogollon Rim. Frey and Yates (1993, p. 10) 
suggested that this grouping questions the validity of Navajo Mexican 
vole as a separate subspecies. However, in order to verify this 
suggestion, specimens would need to be examined from the type locality 
of the Navajo Mexican vole subspecies, which is Navajo Mountain, Utah 
(Frey and Yates 1993, p. 10). The authors recommended additional 
analyses, including larger sample sizes, to clarify the arrangement in 
three separate subspecies (Frey and Yates 1993, p. 10). At that time, 
we continued to recognize the Hualapai Mexican vole subspecies as 
occurring in the Hualapai Mountains.
    Frey and Yates (1995) continued their genetic work on Mexican vole 
subspecies and analyzed 173 specimens from 28 populations (16 from 
Arizona, 10 from New Mexico, 1 from Utah, and 1 from Mexico) using 
protein electrophoresis and mitochondrial DNA. They found that six 
populations (Hualapai Mountains, Hualapai Indian Reservation, Music 
Mountains, Aubrey Cliffs/Chino Wash, Santa Maria Mountains, and 
Bradshaw Mountains) could be the Hualapai Mexican vole subspecies (Frey 
and Yates 1995, p. 9). The authors found unique alleles at two loci in 
these six populations, which identified them as being closely related 
(Frey and Yates 1995, p. 9). Based on geographic proximity, Frey and 
Yates (1995, p. 8) suspected that two other populations (Round Mountain 
and Sierra Prieta) could also be the Hualapai Mexican vole subspecies, 
but they did not have adequate samples for genetic verification.
    Additional genetic analyses were conducted by Busch et al. (2001). 
Busch et al. (2001, p. 4) examined nuclear genetic markers from 42 
specimens across 6 populations in northwestern Arizona (Hualapai 
Mountains, Prospect Valley, Bradshaw Mountains, Sierra Prieta, 
Prescott, and Mingus Mountains) using Amplified Fragment Length 
Polymorphis (AFLP). Additionally, they examined mitochondrial (D-Loop) 
DNA from 83 specimens across 13 populations in Arizona (Hualapai 
Mountains, Prospect Valley, Bradshaw Mountains, Sierra Prieta, 
Prescott, Mingus Mountains, South Rim Grand Canyon, San Francisco 
Mountain, Mogollon Rim, White Mountains, Chuska Mountains, Aubrey 
Cliffs, and Navajo Mountain). Results from their study did not support 
the separation of Mexican voles into three distinct subspecies based on 
nuclear and mitochondrial genetic analyses (Busch et al. 2001, p. 12). 
Populations referred to as the Navajo Mexican vole subspecies from 
Navajo Mountain, Mingus Mountain, San Francisco Peaks, and the Grand 
Canyon South Rim and populations referred to as the Mogollon Mexican 
vole subspecies from the Mogollon Rim, Chuska Mountains, and White 
Mountains were genetically similar to Mexican voles in the Hualapai 
Mountains, Hualapai Indian Reservation, Aubrey Cliffs, Bradshaw 
Mountains, Watson Woods, and Sierra Prieta (Busch et al. 2001, p. 12). 
In summary, the analyses conducted by Busch et al. (2001, p. 12) did 
not support the separation of Arizona populations of M. mogollonensis 
into three subspecies (i.e., M. m. mogollonensis, M. m. navajo, and M. 
m. hualapaiensis) as recognized by Frey and Yates (1993, 1995). 
According to Busch et al. (2001), populations of M. mogollonensis and 
M. m. navajo were not clearly differentiated from M. m. hualapaiensis 
(i.e., the Hualapai Mexican vole).
    Busch et al. (2001, p. 12) suggested that only one subspecies of 
Mexican vole occurs in Arizona, but they did not suggest a new 
subspecies name to which the currently named subspecies of Mexican 
voles should be reclassified as. Further, Busch et al. (2001, p. 12) 
suggested that voles from the White Mountains and Chuska Mountains 
could be a different subspecies or may simply show some genetic 
differentiation due to geographic separation; however, their analysis 
was inconclusive. Even though Busch et al. (2001, p. 12) did not 
suggest a name to assign to the only subspecies of Mexican voles in 
Arizona, the AGFD's petition (2004, p. 4) referred to Busch et al.'s 
(2001) single subspecies as Microtus mexicanus hualpaiensis.
    In 2003, AGFD sent the Busch et al. (2001) report to five genetic 
experts representing the U.S. Geological Survey's Arizona Cooperative 
Fish and Wildlife Research Unit, the Conservation Breeding Specialist 
Group, the University of Colorado at Boulder, Oklahoma State 
University, and New Mexico State University for peer review. Four of 
the five reviewers concurred with the conclusions of Busch et al. 
(2001) that all populations in Arizona could be referred to as M. m. 
hualpaiensis. One of the five reviewers concluded that populations from 
the Hualapai Mountains, Music Mountains, and Hualapai Reservation form 
a closely related group distinct from other populations in Arizona 
based on the reviewer's work in 1993 and 1995. This reviewer further 
stated that M. m. hualpaiensis is a valid subspecies based on 
morphologic, genetic, and biogeographical data.
    Busch et al.'s (2001) genetic report and reviews by the genetic 
experts were then sent to two mammalian taxonomy experts familiar with 
the research surrounding voles for additional review. One of the 
taxonomic reviewers agreed with the one dissenting genetic reviewer 
from 2003, who believed the data supported M. m. hualpaiensis in five 
locations. The other taxonomic reviewer concluded that there is no 
basis to consider the three subspecies of Mexican voles (Hualapai, 
Navajo, and Mogollon) separately. This second taxonomic reviewer stated 
that data used by Hoffmeister (1986) were insufficient to recognize 
three subspecies based on morphology, and that the genetic analyses 
conducted by Frey and Yates (1993; 1995) and Busch et al. (2001) were 
subject to methodological problems (AGFD 2004, p. 4). The second 
taxonomic reviewer asserted that all three subspecies should be 
considered as one subspecies, Microtus mogollonensis mogollonensis 
(common name not suggested).
    According to AGFD, the field and laboratory studies concluded that 
M. m. hualaiensis exists in at least seven populations and perhaps as 
many as 14 populations (one is in Utah), whereas only one population 
was known prior to listing. Field surveys demonstrated that the 
Hualapai Mexican vole is not as rare as it was once thought to be. 
Prior to listing, only 15 specimens from seven locations (all within 
the Hualapai Mountains) were known. The genetic studies mentioned 
above, in conjunction with trapping success, demonstrate that M. m. 
hualpaiensis populations are widespread and not

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restricted to a single mountain range (AGFD 2004, p. 9).
    The AGFD provided a summary of factors affecting the Hualapai 
Mexican vole in their 2004 status assessment and petition. AGFD stated 
that the species is found in more xeric and mesic habitats than other 
vole species, so trampling of seeps and spring areas by cattle is no 
longer considered a threat to Hualapai Mexican voles as previously 
thought when the subspecies was listed (AGFD 2004, pp. 5-6). Further, 
AGFD stated that because the Hualapai Mexican voles' range is not as 
restricted as once thought, grazing and recreational uses are no longer 
threats to the subspecies (AGFD 2004, p 7). Finally, based on five 
genetic and two taxonomic reviews, the AGFD stated that all 14 
populations analyzed by Busch et al. (2001) could be considered a 
single species, rather than three subspecies (AGFD 2004; p. 4).
    In summary, the various analyses and reviews present multiple 
interpretations of the taxonomy and distribution of Hualapai Mexican 
voles in Arizona, none of which correlates to that of our original 
listing. The 1987 final listing rule for the Hualapai Mexican vole (52 
FR 36776; October 1, 1987) relied on the best available information at 
the time, and only included Hualapai Mexican voles found in the 
Hualapai Mountains. The various published and unpublished reports all 
offer different conclusions about which populations may or may not be 
Hualapai Mexican voles. At this time, the best available scientific 
information presents conflicting information on the taxonomy of Mexican 
voles in general. The majority (i.e., five out of seven) of scientists 
who reviewed the ``Hualapai vole (Microtus mogollonensis hualapaiensis) 
Genetic Analysis'' report by Busch et al. (2001) determined that 
Hualapai Mexican voles (Microtus mexicanus hualpaiensis) are not 
genetically distinct from other vole subspecies in Arizona. The best 
available science no longer supports the recognition of a separate 
Hualapai Mexican vole subspecies. Although the Hualapai Mexican vole 
subspecies is no longer considered a valid taxonomic entity, the 
scientific community agrees that the populations that were previously 
identified as the Hualapai Mexican vole subspecies are part of the 
larger Mexican vole species (Microtus mexicanus).
    The Mexican vole is recognized by the scientific community as a 
species, including the International Union for Conservation of Nature 
(IUCN) and ITIS. The Mexican vole is listed as least concern by IUCN in 
view of its wide distribution, presumed large population, occurrence in 
a number of protected areas, and because it is unlikely to be declining 
at nearly the rate required to qualify for listing in a threatened 
category ([Aacute]lvarez-Casta[ntilde]eda, S.T. & Reid, F. 2016). The 
Mexican vole species occurs from the southern Rocky Mountains southward 
in the Sierra Madre of Mexico to central Oaxaca Mexico (Tamarin 1985 p. 
99). The existence of several populations improves the ability of the 
species to withstand environmental and demographic stochasticity (for 
example, wet or dry, warm or cold years); the ability of the species to 
adapt over time to long-term changes in the environment (for example, 
climate changes); and the ability of the species to withstand 
catastrophic events (for example, droughts, hurricanes). In general, 
the more populations there are, the more likely the species is to 
sustain populations over time, even under changing environmental 
conditions. The distribution of the Mexican vole populations allows for 
sustained populations into the future. Based on the best available 
scientific and commercial data at this time, we find that the original 
data for classification were in error, and we are removing the Hualapai 
Mexican vole (Microtus mexicanus hualpaiensis) from the List under the 
Act.

Summary of Comments and Recommendations

    In our June 4, 2015, combined 12-month finding and proposed rule 
(80 FR 31875), we requested that all interested parties submit comments 
or information concerning the proposed delisting of the Hualapai 
Mexican vole. We provided notification of this document through email, 
letters, and news releases to the appropriate Federal, State, and local 
agencies; county governments; elected officials; media outlets; local 
jurisdictions; scientific organizations; interested groups; and other 
interested parties. We also posted the document on our Web site 
(https://www.fws.gov/news/ShowNews.cfm?ref=service-proposes-delisting-the-hualapai-mexcian-vole&_ID=35074).
    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270), we solicited expert opinions from five knowledgeable 
individuals with scientific expertise that included genetics, 
conservation biology, and ecology of voles and the ecosystems upon 
which they depend. We received comments from two peer reviewers 
associated with academic research institutions. One researcher noted 
that the data gathered and analyzed to date do not appear to support an 
integrative approach to taxonomy. For example, using a current genome-
side marker like single nucleotide polymorphisms (or SNPs) would be 
preferable. The same researcher stated that there is a strong reliance 
on mitochondrial DNA and lack of a thorough study of morphology, 
behavior, and ecology of this subspecies. The other peer reviewer noted 
that in the case of M. m. hualpaiensis, there is little morphologic and 
genetic evidence to distinguish it from its nearby conspecifics (i.e., 
other vole subspecies). This reviewer concluded that the current data 
are not sufficient to support the subspecific recognition of M. m. 
hualpaiensis. Both reviewers recommended continued studies.
    We reviewed all comments we received from the peer reviewers and 
the public for substantive issues and new informative regarding the 
proposed delisting of the Hualapai Mexican vole. We received four 
comments on the proposed rule. Two were in favor of delisting the 
Hualapai Mexican vole. One commenter provided a conservation status 
review to support the proposed delisting by documenting the current 
conservation status of the Hualapai Mexican vole and its likely 
synonymous populations, as well as an evaluation of potential threats 
to the larger, taxonomically valid subspecies. One commenter opposed 
the delisting of the Hualapai Mexican vole. Substantive comments we 
received during the comment period are addressed below.
    (1) Comment: There is a concern that delisting the vole is based on 
conflicting scientific information instead of a peer review based on 
the five delisting factors (see section 4(a)(1) of the Act). In order 
to delist the subspecies, the Service must evaluate this erroneous 
classification by seeking a peer review pursuant to the five factors.
    Our Response: The removal of the vole from the Federal List of 
Endangered and Threatened Wildlife is based on recent peer reviewed 
data indicating the original data for classification were in error. Our 
June 4, 2015, proposed rule (80 FR 31875) was based on peer reviewed 
studies and has separately undergone peer review, as explained below. 
The regulations at 50 CFR 424.11(d) state that a species may be 
delisted if (1) it becomes extinct, (2) it recovers, or (3) the 
original classification data were in error. Our finding is that the 
original classification data were in error. Further, it is the policy 
of the Service to incorporate independent peer review in listing (and 
recovery) activities by soliciting the expert opinions relating to 
taxonomy, population models, and supportive biological and ecological 
information for

[[Page 28586]]

species or subspecies under consideration of a listing decision (59 FR 
34270; July 1, 1994). We sought the expert opinions of five appropriate 
independent specialists regarding the science in the June 4, 2015, 
proposed rule to delist the Hualapai Mexican vole. The purpose of peer 
review was to ensure that our delisting decision is based on 
scientifically sound data, assumptions, and analyses. We sent copies of 
the proposed rule and supporting documents to the peer reviewers 
immediately following publication in the Federal Register.
    We received reviews from two peer reviewers. One of the peer 
reviewers stated that although it is still unclear exactly what the 
numbers are, it is clear that the numbers of these voles in the 
mountains of western Arizona are larger than was earlier suspected. 
Kime et al. (1995) found 21 locations harboring voles. The species is 
not tied to rare, moist habitats the way other species of Microtus are, 
and thus gene flow may be greater than expected earlier. The other peer 
reviewer stated that in the case of M. m. hualpaiensis, there is little 
morphologic and genetic evidence to distinguish it from its nearby 
conspecifics (i.e., other species of voles). Also, the 12-month finding 
found no natural history or biologically significant information on M. 
m. hualpaiensis to distinguish individuals from the Hualapai Mountains 
from other populations in the region. Although voles from the Hualapai 
Mountains may be on an evolutionary trajectory in the direction of a 
``subspecies,'' this trajectory is mostly likely very recent and 
insufficient to warrant description as an independent subspecies at 
this time. Given our review of the scientific and commercial data 
available for the Hualapai Mexican vole subspecies (M. m. 
hualpaiensis), we conclude that it is not a valid taxonomic entity for 
listing.
    (2) Comment: The Service should conduct a detailed study and 
analysis on the vole's genetics prior to taking any action to 
reclassify the subspecies. Conflicting data on genetics should be 
resolved prior to agency action and should not be used as a 
justification to delist. Further the Service must rationally explain 
why the uncertainty counsels in favor of delisting now, rather than, 
for example, more study.
    Our Response: While we recognize that more studies are always 
beneficial, our action is based on a thorough review of the best 
available scientific and commercial data, which indicates that the 
currently listed subspecies was listed in error as it is not a valid 
taxonomic entity. One of the peer reviewers stated that both AFLP and 
D-loop sequences are appropriate genetic markers for the level of 
taxonomy in question, and both markers lack support for individuals 
from the Hualapai Mountains forming an independent, genetic lineage. 
Further, the peer reviewer also stated that the current data are not 
sufficient to support the subspecific recognition of voles from the 
Hualapai Mountains, M. m. hualpaiensis. While both peer reviewers 
suggested that more genetic studies be conducted, the Service has 
relied on the best available scientific and commercial data at this 
time, as required under the Act.
    (3) Comment: The Service is unable to show by the best scientific 
or commercial data available that classifying the Hualapai Mexican vole 
as an endangered subspecies of the greater Mexican vole species was in 
error.
    Our Response: According to our regulations at 50 CFR 424.11(d), we 
may delist a species if the best available scientific and commercial 
data indicate that the species is neither endangered or threatened for 
the following reasons: (1) The species is extinct; (2) the species has 
recovered and is no longer endangered or threatened; and/or (3) the 
original scientific data used at the time the species was classified 
were in error. We determine that the original classification is in 
error because there is sufficient evidence that the currently listed 
entity for the Hualapai Mexican vole is not a valid taxonomic 
subspecies. This evidence was not available to the Service at the time 
we listed the subspecies in 1987. The various analyses and reviews 
present multiple interpretations of the taxonomy and distribution of 
Mexican voles in Arizona, none of which correlates to that of our 
original listing. The final listing rule for the Hualapai Mexican vole 
(52 FR 36776; October 1, 1987) relied on the best available information 
at the time, and only included Mexican voles found in the Hualapai 
Mountains. The various published and unpublished reports we have used 
to make this decision all offer different conclusions about which 
populations may or may not be Hualapai Mexican voles. At this time, the 
best available scientific information presents conflicting information 
on the taxonomy of Mexican voles in general, and no longer supports the 
recognition of a separate Hualapai Mexican vole subspecies. Although 
reviews of the published and unpublished reports have inconsistent 
conclusions because of differences in data sets and genetic analyses, 
the Service and each of the peer reviewers agreed that the currently 
listed entity for the Hualapai Mexican vole is no longer a valid 
taxonomic subspecies. However, the populations that were previously 
identified as the Hualapai Mexican vole subspecies are recognized by 
the majority of the scientific community, including IUCN and ITIS, as 
part of a larger taxonomic species level of Mexican voles (Microtus 
mexicanus). Therefore, the original scientific data used at the time 
the subspecies was classified as an endangered subspecies were in 
error.

Listable Entity Determination

    The petition asserts that the Hualapai Mexican vole should be 
delisted. Working within the framework of the regulations for making 
delisting determinations, as discussed above, the petition asserts that 
the original data we used in our recognition of the Hualapai Mexican 
vole as a subspecies, and thus a listable entity under the Act, were in 
error. In determining whether to recognize the Hualapai Mexican vole as 
a valid (distinguishable) subspecies, we must base our decision on the 
best available scientific and commercial data. Additionally, we must 
provide transparency in application of the Act's definition of a 
species through careful review and analyses of all the relevant data.
    Under section 3 of the Act and our implementing regulations at 50 
CFR 424.02, a ``species'' includes any subspecies of fish or wildlife 
or plants, and any distinct population segment of any species of 
vertebrate fish or wildlife which interbreeds when mature. As such, a 
``species'' under the Act may include any taxonomically defined species 
of fish, wildlife, or plant; any taxonomically defined subspecies of 
fish, wildlife, or plant; or any distinct population segment of any 
vertebrate species as determined by us per our Policy Regarding the 
Recognition of District Vertebrate Population Segments [DPSs] Under the 
Endangered Species Act (61 FR 4722; February 7, 1996). We note that 
Congress has instructed the Secretary to exercise this authority with 
regard to DPS's ``* * * sparingly and only when the biological evidence 
indicates that such action is warranted.''
    Our implementing regulations provide further guidance on 
determining whether a particular taxon or population is a species or 
subspecies for the purposes of the Act: ``the Secretary shall rely on 
standard taxonomic distinctions and the biological expertise of the 
Department and the scientific community concerning the relevant 
taxonomic group'' (50 CFR 424.11(a)). For each species, section 
4(b)(1)(A) of the Act

[[Page 28587]]

mandates that we use the best scientific and commercial data available 
for each individual species under consideration. Given the wide range 
of taxa and the multitude of situations and types of data that apply to 
species under review, the application of a single set of criteria that 
would be applicable to all taxa is not practical or useful. In 
addition, because of the wide variation in kinds of available data for 
a given circumstance, we do not assign a priority or weight to any 
particular type of data, but must consider it in the context of all the 
available data for a given species.
    For purposes of being able to determine what is a listable entity 
under the Act, we must necessarily follow a more operational approach 
and evaluate and consider all available types of data, which may or may 
not include genetic information, to determine whether a taxon is a 
distinguishable species or subspecies. As a matter of practice, and in 
accordance with our regulations, in deciding which alternative 
taxonomic interpretations to recognize, the Service will rely on the 
professional judgment available within the Service and the scientific 
community to evaluate the most recent taxonomic studies and other 
relevant information available for the subject species. Therefore, we 
continue to make listing decisions based solely on the basis of the 
best scientific and commercial data available for each species under 
consideration on a case-specific basis.
    In making our determination whether we recognize the Hualapai 
Mexican vole as a distinguishable subspecies and, thus, whether the 
petitioned action is warranted, we considered all available data that 
may inform the taxonomy of the Hualapai Mexican vole, such as ecology, 
morphology, and genetics.
    In determining whether to recognize the Hualapai Mexican vole as a 
distinguishable subspecies, we must first define the criteria used to 
make this decision given the available information. Within the 
taxonomic literature, there are no universally agreed-upon criteria for 
delineating, defining, or diagnosing subspecies boundaries. Each 
possible subspecies has been subject to unique evolutionary forces, 
different methods of selection will act on each subspecies (genetic 
drift versus allopatric speciation), and the potential divergence time 
(recent versus more distant) will, therefore, lead to different 
signals, particularly genetically; as such, the methods for detecting 
each will be different (Amec 2015, pp. 101-102). Therefore, we conclude 
that the best scientific and commercial information available indicate 
that the Hualapai Mexican vole is not a distinguishable subspecies, and 
we, therefore, do not recognize it as a listable entity under the Act. 
(A ``listable entity'' is one that qualifies as a ``species'' under the 
definition in section 3 of the Act and is thus eligible to be listed as 
an endangered species or a threatened species.) Because we found that 
the Hualapai Mexican vole is not a valid listable entity, conducting a 
distinct population segment (DPS) analysis would be inappropriate.

Delisting Analysis

    After a review of all information available, we are removing the 
Hualapai Mexican vole from the List of Endangered and Threatened 
Wildlife (List). Section 4(a)(1) of the Act and regulations (50 CFR 
part 424) issued to implement the listing provisions of the Act set 
forth the procedures for adding species to or removing them from the 
List. The regulations at 50 CFR 424.11(d) state that a species may be 
delisted if (1) it becomes extinct, (2) it recovers, or (3) the 
original classification data were in error.
    At this time, the best available scientific information presents 
conflicting information on the taxonomy of Mexican voles in general, 
and no longer supports the recognition of a separate Hualapai Mexican 
vole subspecies. Reviews of the published and unpublished reports have 
inconsistent conclusions because of different genetic analyses and data 
sets. However, there is sufficient evidence to indicate that the 
currently listed entity for the Hualapai Mexican vole is no longer a 
valid taxonomic subspecies. Additionally, the Mexican vole is listed as 
least concern by IUCN in view of its wide distribution, presumed large 
population, occurrence in a number of protected areas, and because it 
is unlikely to be declining at nearly the rate required to qualify for 
listing in a threatened category ([Aacute]lvarez-Casta[ntilde]eda, S.T. 
& Reid, F. 2016). We consider the entity that was previously described 
as Hualapai Mexican vole (Microtus mexicanus hualpaiensis) to be part 
of the Mexican vole species (Microtus mexicanus). The Mexican vole 
species ranges from the southern Rocky Mountains in southern Utah and 
Colorado, through central Arizona and New Mexico, and throughout the 
interior of north and central M[eacute]xico in the Sierra Madre 
Mountains, as far south as central Oaxaca, Mexico (Tamarin 1985, p. 
99).
    Based on the best available scientific and commercial data, we have 
determined that the Hualapai Mexican vole is not a valid taxonomic 
subspecies, and therefore, is not a listable entity under the Act. In 
conclusion, we find that the Hualapai Mexican vole (Microtus mexicanus 
hualpaiensis) must be removed as a listed subspecies under the Act 
because the original scientific data used at the time the subspecies 
was classified were in error.

Effects of the Rule

    This final rule revises 50 CFR 17.11(h) to remove the Hualapai 
Mexican vole from the Federal List of Endangered and Threatened 
Wildlife. Because no critical habitat was ever designated for this 
subspecies, this rule will not affect 50 CFR 17.95.
    On the effective date of this rule (see DATES, above), the 
prohibitions and conservation measures provided by the Act, 
particularly through sections 7 and 9, no longer apply to this 
subspecies. Federal agencies are no longer required to consult with the 
Service under section 7 of the Act in the event that activities they 
authorize, fund, or carry out may affect the Hualapai Mexican vole.

Required Determinations

National Environmental Policy Act

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act of 1969, need not be prepared in connection 
with regulations adopted pursuant to section 4(a) of the Act. We 
published a notice outlining our reasons for this determination in the 
Federal Register on October 25, 1983 (48 FR 49244).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994, 
``Government-to-Government Relations with Native American Tribal 
Governments'' (59 FR 22951), Executive Order 13175, and the Department 
of Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. Therefore, we solicited 
information from Native American Tribes during the proposed rule's 
comment periods to determine potential effects on them or their 
resources that may result from the delisting of the Hualapai Mexican 
vole. No comments were received from Native American Tribes.

References Cited

    A complete list of all references cited in this rule is available 
on http://

[[Page 28588]]

www.regulations.gov, or upon request from the Field Supervisor, Arizona 
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).

Authors

    The primary authors of this rule are the staff members of the 
Arizona Ecological Services Field Office, U.S. Fish and Wildlife 
Service (see ADDRESSES).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Regulation Promulgation

    Accordingly, we amend part 17, subchapter B of chapter I, title 50 
of the Code of Federal Regulations, as set forth below:

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

0
1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, unless 
otherwise noted.


Sec.  17.11  [Amended]

0
2. Amend Sec.  17.11(h) by removing the entry for ``Vole, Hualapai 
Mexican'' from the List of Endangered and Threatened Wildlife.

    Dated: May 25, 2017.
James W. Kurth,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2017-13162 Filed 6-22-17; 8:45 am]
BILLING CODE 4333-15-P